Lead-based alloys containing small amounts of antimony together with other elements such as arsenic and tin have been used to make grids for lead-acid batteries. See, for example, Peters U.S. Pat. No. 3,912,537, Nijhawan et al. U.S. Pat. No. 3,990,893 and Nijhawan U.S. Pat. No. 3,801,310. Lead-antimony alloys have also been used for other conductive battery components such as intercell connectors/straps, but it has been recognized that strap alloys and grid alloys have different requirements and therefore different compositions. Alloys for cast-on straps, for example, must have the ability to bond to the grid lugs during the casting process.
Lead-based alloys containing antimony and other elements have long been used to form cast-on battery straps. See, for example, Mix U.S. Pat. No. 3,764,386 and "New Developments In Battery Strap Alloys", The Battery Man, September 1989, p. 18. Rao et al. U.S. Pat. No. 5,169,734 describes a lead-based strap alloy consisting essentially of from about 3.0 to 3.3 wt. % antimony, about 0.04 to 0.07 wt. % arsenic, about 0.04 to 0.07 wt. % tin, and about 0.014 to 0.020 wt. % selenium. When used to make battery straps for use in lead-acid batteries, this alloy has good mechanical properties and the important ability to withstand prolonged exposure to high temperatures. The Rao et al. patent places great emphasis on the importance of the foregoing proportions, but provides no explanation as to why using each ingredient in the stated range is critical to obtaining the desired properties. The Rao et al. composition employs very low amounts of tin and arsenic, and the beneficial effects of these ingredients are correspondingly limited.
The present invention details the importance of each of antimony, tin, arsenic and selenium in a lead-based strap alloy and provides the surprising result that superior corrosion resistance can be obtained outside the narrow ranges stated in the Rao et al. patent.